This invention generally relates to a small-sized rotary switch. More particularly, the present invention relates to improvements in a stopper mechanism of a small-sized rotary switch.
Conventionally, a stopper mechanism is constructed, as shown in FIG. 1, in the following manner. A mounting screw 1 is provided on a cap 2 which is provided at its top portion with a plurality of apertures 2a. A pawl formed stopper 3 provided at its center with an opening 3a is fitted onto the mounting screw 1 of the cap 2 so that the pawl 3b is selectively inserted into one of the apertures 2a of the cap 2. The stopper 3 is then fixed to the cap 2 by tightening nuts 4 onto the screw 1. In the aforementioned construction, when a projection 5a, provided on a rotary shaft 5, engages with the pawl 3b of the stopper, the rotary shaft 5 is stopped.
Although there is no particular problem in the mechanical strength of the mechanism thus described, the problem in recent years of damage due to the environment arises from the miniaturization of switches. Namely, because of the presence of apertures 2a provided on the top portion of the cap 2 for insertion the pawl 3b of the stopper 3, the problem arises in that sulfide gas promoting oxidization of the electrical contacts or dust in the air intrudes into the cap through the apertures and causes an obstacle to the engagement between the contacts.
Furthermore, in recent years, small-sized switches tend to be used particularly in such a manner that the terminals of the switches are directly welded onto a printed circuit board. In such a case, there is a so-called washing step during which flux produced in welding is washed away after the small-sized switches are welded in an automatic welding vessel. At that time, in the conventional construction of switches, washing liquid flows onto the switch body through the apertures 2a of the cap, and therefore there is the possibility and thus disadvantage that the flux will not be washed out by a normal washing device. Consequently, the washing must be carefully controlled by using a brush for each switch, which is quite troublesome.